Plutonium

2 definitions found

From WordNet (r) 2.0 [wn]:

  plutonium
       n : a solid silvery gray radioactive transuranic element  whose
           atoms can be split when bombarded with neutrons; found in
           minute quantities in uranium ores but is usually
           synthesized in nuclear reactors; 13 isotopes are known
           with the most important being plutonium 239 [syn: {Pu}, {atomic


           number 94}]

From Elements database 20001107 [elements]:

  plutonium
  Symbol: Pu
  Atomic number: 94
  Atomic weight: (242)
  Dense silvery radioactive metallic transuranic element, belongs to the
  actinoids. Pu-244 is the most stable isotope with a half-life of 7.6*10^7
  years. Thirteen isotopes are known. Pu-239 is the most important, it
  undergoes nuclear fission with slow neutrons and is hence important to
  nuclear weapons and reactors. Plutonium production is monitored down to
  the gram to prevent military misuse. First produced by Gleen T. Seaborg,
  Edwin M. McMillan, J.W. Kennedy and A.C. Wahl in 1940.